Baikonur Cosmodrome.

Baikonur Cosmodrome in Kazakhstan is the world's first and largest operational spaceport, established by the USSR in 1955 and still used for crewed launches. Crews and ground staff have at times reported unexplained lights near launch windows, which skeptics largely attribute to rocket-plume optical effects and high-altitude exhaust phenomena. The facility is fully documented; the anomaly reports are alleged and largely prosaic.